6533b823fe1ef96bd127ea9e

RESEARCH PRODUCT

Evolution of Complex Acoustic Signals in Drosophila Species

subject

description

species produce complex acous-tic cues, so-called courtship songs, while pursuing a female.In most of the over 100 species studied so far (see thelist of these species in Hoikkala, 2005), such cues areproduced by wing vibration. Other mechanisms of songproduction include abdomen purring (Hoy, Hoikkala, &Kaneshiro, 1988) and rapid vibrations of the whole body(Ritchie & Gleason, 1995). The carrier frequency of songsproduced through any of these actions ranges from 150 to500Hz. A hitherto unknown mechanism enables males ofsome Hawaiian species to generate songs of up to 15,000Hz(Hoikkala, Hoy, & Kaneshiro, 1989).The structure of the courtship songs of closely relatedspecies often reflects phylogenetic relationships of thespecies, implying that the songs may be diverging as a by-product of genetic divergence and/or drift. The course ofsong evolution may also be driven or constrained by vari-ous forms of selection pressure, causing or reinforcing songdivergence at population and species level or, conversely,inhibiting differentiation. Darwin (1871) proposed that sex-ual selection promotes the origin and exaggeration of pre-copulatory male displays which enable females to choosethe best among an array of potential mates. However, sex-ual selection need not be the exclusive, nor the predominant,selection pressure affecting song evolution. Courtship songis to some extent species-specific and can as such contributeto reproductive isolation and hence, ultimately, to speciation.The courtship songs of